where \(H_0\)  is the present expansion rate, \(n \simeq 0.96\) 
is the scalar power index, \(\delta _H \simeq 4.6 \cdot 10^{-5}\) 
is the amplitude of adiabatic density perturbations when they
reenter the horizon, \(\Omega _m \simeq \)  0.3 is the fraction of
the critical energy density in matter today, and
\(D_1(t_0) \simeq 0.8\)  is the growth function. Eq. (REF )
and the various parameter estimates are taken from ref.
[1]}. Eq. (REF ) applies on wavevector scales
of order \(H_0^{-1}\) . We extrapolate it, over approximately 13
orders of magnitude, to modes that enter the horizon shortly
before the QCD phase transition. This yields
\({8 \pi G H_I^2 \over 9 \epsilon } \equiv C \simeq 4.9 \cdot 10^{-9}~~\ .\) 
